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| 2. |
- Ahmadi Naghadeh, Reza, 1982, et al.
(författare)
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A laboratory characterisation of the response of intact chalk to cyclic loading
- 2022
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Ingår i: Geotechnique. - : Thomas Telford Ltd.. - 0016-8505 .- 1751-7656. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the cyclic behaviour of chalk, which has yet to be studied comprehensively. Multiple undrained high-resolution cyclic triaxial experiments on low- to medium-density intact chalk, along with index and monotonic reference tests, define the conditions under which either thousands of cycles could be applied without any deleterious effect, or failure could be provoked under specified numbers of cycles. Intact chalk's response is shown to differ from that of most saturated soils tested under comparable conditions. While chalk can be reduced to putty by severe two-way displacement-controlled cycling, its behaviour proved stable and nearly linear visco-elastic over much of the one-way, stress-controlled loading space examined, with stiffness improving over thousands of cycles, without loss of undrained shear strength. However, in cases where cyclic failure occurred, the specimens showed little sign of cyclic damage before cracking and movements on discontinuities led to sharp pore pressure reductions, non-uniform displacements and the onset of brittle collapse. Chalk's behaviour resembles the fatigue response of metals, concretes and rocks, where micro-shearing or cracking initiates on imperfections that generate stress concentrations; the experiments identify the key features that must be captured in any representative cyclic loading model.
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| 3. |
- Ahmadi-Naghadeh, Reza, et al.
(författare)
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A new isotropic specimen preparation method from slurry for both saturated and unsaturated triaxial testing of a low-plasticity silt
- 2019
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Ingår i: ASTM geotechnical testing journal. - : ASTM International. - 0149-6115 .- 1945-7545. ; 42:4, s. 854-879
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Tidskriftsartikel (refereegranskat)abstract
- A new procedure for the preparation of low-plasticity silt specimens that are isotropically reconstituted from slurry is developed for use in both saturated and unsaturated soil testing. Spatial variations of the water content and grain size distribution were examined to confirm the uniformity of the specimens (regarding void radio and segregation). The new preparation method results in a homogeneous specimen, which has a simple stress history. The repeatability of the proposed method in preparing identical specimens was verified for both saturated and unsaturated soil testing. The strength and volumetric behavior of specimens prepared by the introduced method are compared with those of moist-tamped compacted specimens and one-dimensionally reconstituted slurry specimens by performing consolidated drained triaxial tests. The microstructure of the specimens prepared with different methods was examined using Scanning Electron Microscopy and Mercury Intrusion Porosimetry. The test results indicate that silt specimens could exhibit either dilative or contractive behavior at normal consolidated conditions, depending on the microstructure.
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| 4. |
- Ahmadi-Naghadeh, Reza, et al.
(författare)
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Exponential Equation for Predicting Shear Strength Envelope of Unsaturated Soils
- 2019
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Ingår i: International Journal of Geomechanics. - : American Society of Civil Engineers (ASCE). - 1532-3641 .- 1943-5622. ; 19:7
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Tidskriftsartikel (refereegranskat)abstract
- An exponential equation is introduced to predict the nonlinear variation of shear strength with matric suction for unsaturated soils. The proposed equation involves three constant parameters, two of which are effective shear strength parameters (i.e., ′ and c′). The third parameter is the maximum capillary cohesion, c″max, which is the maximum possible increase in shear strength due to matric suction. A procedure for the determination of c″max from the soil-water characteristic curve (SWCC) is devised. The proposed equation is validated through a series of constant-suction consolidated drained triaxial tests conducted on specimens reconstituted by isotropic consolidation from the slurry state. In addition, the validity of the equation is investigated by applying it to the test results of five other soils that were available in the literature for the low-suction range (i.e., up to 1,500 kPa). A comparative study on the prediction of shear strength was carried out between the proposed equation and six other shear strength equations found in the literature. The results show that the proposed equation provides reliable predictions of the shear strength of unsaturated soils when the shear strength converges to an asymptotic value at the residual water content.
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| 5. |
- Ahmadi-Naghadeh, Reza, et al.
(författare)
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Volume change measurement in triaxial tests by monitoring cell fluid volume based on viscoelastic behavior of the test setup
- 2017
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Ingår i: ASTM geotechnical testing journal. - : ASTM International. - 0149-6115 .- 1945-7545. ; 40:4, s. 683-697
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Tidskriftsartikel (refereegranskat)abstract
- A novel procedure was developed to measure the total volume change of the unsaturated soils in triaxial testing. The principle of the proposed method was based on cell fluid volume measurements corrected by the assumption of viscoelastic behavior for the triaxial setup. Calibration and parameter determination procedures of the model are devised, and the presented model is implemented into a MATLAB code. The proposed method was validated through a series of consolidated drained triaxial tests on saturated specimens, by comparing the changes in volume measurement of proposed method and conventional measurement (pore fluid). The accuracy in volume measurement during consolidation and shear stages of these tests was between 0.09 and 0.32 cm3, which is on par with or better than more complex and expensive alternatives found in the literature. Repeatability of the proposed technique in measurement of the volume change was also investigated through a series of suction controlled unsaturated soil tests.
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| 6. |
- Andersson, Roy, et al.
(författare)
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Total productive maintenance in support processes : an enabler for operation excellence
- 2015
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Ingår i: Total Quality Management and Business Excellence. - : Informa UK Limited. - 1478-3363 .- 1478-3371. ; 26:9-10, s. 1042-1055
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Tidskriftsartikel (refereegranskat)abstract
- In order to stay competitive in today's marketplace, it is vital to reduce activities that do not create value. Lean production has in the last decade been seen as a philosophy to reduce non-value time. The office environment often presents a major improvement opportunity to reduce non-value time. Lean contributes positively to business performance applied in a manufacturing context and is also suggested to do the same in a service context. The purpose of the paper is to analyse and determine how total productive maintenance (TPM) can be applied within the support process and to identify effects from an employee and business perspective. A case study has been performed and a qualitative research approach was selected. Empirical data were gathered by using semi-structured interviews at one case company, but from several teams that had applied TPM. The result was then used as an inductive approach to explore how TPM can be applied in a support process. To implement and apply TPM within an office context, it should be structured in three steps (i) define, (ii) implement and (iii) sustain. TPM should be conducted as a part of the ordinary day-to-day work. The planning and discussions connected to TPM can be included in regular daily departmental stand-up meetings' involving everybody. The work with 5S and maintenance should also be a part of the TPM structure, connecting it as a system and not as an isolated activity. TPM can create value from both a business and an employee perspective. In the employee perspective, TPM reduces the risk of missing/forgetting areas of responsibility and creates more involvement. In the business perspective, objectives such as cost and quality are improved, but TPM also enables the reduction of waste.
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| 7. |
- Andrae, Anders, 1973, et al.
(författare)
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Uncertainty estimation by Monte Carlo simulation applied to life cycle inventory of cordless phones and microscale metallization processes
- 2004
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Ingår i: IEEE transactions on electronics packaging manufacturing (Print). - 1521-334X .- 1558-0822. ; 27:4, s. 233-245, s. 206-217
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on uncertainty analysis, that is, how the input data uncertainty affects the output data uncertainty in small but realistic product systems. The motivation for the study is to apply the Monte Carlo simulation for uncertainty estimation in life cycle inventory and environmental assessment of microelectronics applications. The present paper addresses the question whether there is an environmental advantage of using digital enhanced cordless telecommunications (DECT) phones instead of global system for mobile (GSM) phones in offices. This paper also addresses the environmental compatibility of electrochemical pattern replication (ECPR) compared to classical photolithography-based microscale metallization (CL) for pattern transfer. Both environmental assessments in this paper consider electricity consumption and CO2 emissions and the projects undertaken are two comparative studies of DECT phone/GSM phone and ECPR/CL, respectively. The research method used was probabilistic uncertainty modeling with a limited number of inventory parameters used in the MATLAB tool. For the DECT/GSM study the results reflects the longer DECT technical life which is an environmental advantage. For the electrochemical pattern replication (ECPR)/classical photolithography based microscale metallization (CL) study the results reflects the fewer number of process steps and the lower electricity consumption needed by the ECPR to reach the functional unit. The difference in results is large enough to be able to draw conclusions, as the processes, having the highest electricity consumption within the system boundaries have been determined. Based on an earlier work, a straightforward method to include uncertainty for input life cycle inventory data is used to quantify the influence of realistic errors for input data in two microelectronic applications. The conclusion is that the ECPR technology is more electricity efficient than CL in producing one layer of copper on a silicon wafer having a diameter of 20.32 cm. Furthermore, the longer technical life of a cordless DECT phone is reflected in an electricity/CO2 comparison with a GSM phone, if office use is considered. Reasonable uncertainty intervals, used for the input life cycle inventory data for the studied DECT/GSM and ECPR/CL system, does affect the outcome of calculation of emission of CO2, but not to the degree that conclusions are not valid. Different uncertainty intervals and probability distributions could apply for different types of data and the interrelated input data dependencies should be investigated. Today there exist very few life cycle inventory (LCI) data with the range of uncertainty for input and output elements. It must be emphasized that the upcoming LCI databases should have standard deviation characterized LCI data just as the Swiss ecoinvent LCI database. More inventory parameters and probability distributions characteristic for microsystems could be included and error analysis should be applied to future life inventory methodology, especially for future packaging concepts such as system-in-a-package and system-on-a-chip comparisons.
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| 8. |
- Anter, Karin Fridell, et al.
(författare)
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SYN-TES INTERDISCIPLINARY RESEARCH ON COLOUR AND LIGHT
- 2012
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Ingår i: Proceedings for Interim Meeting of the International Colour Association (AIC); AIC 2012 “In Color We Live: Color and Environment”, 22 – 25 September 2012, Taipei, Taiwan. - : The International Colour Association. ; , s. 80-83, s. 80-83
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Konferensbidrag (refereegranskat)abstract
- Colour and light have largely been considered as belonging to two different fields of knowledge, having disparate theoretical, terminological and methodological traditions. This creates a ground for misunderstandings and obstructs a fruitful interdisciplinary and interprofessional collaboration. A survey over international research literature from 2006 -2011 shows that there has been only little research on the spatial interaction between colour and light, but that the interest for this area has recently increased. The interdisciplinary Nordic research project SYN-TES: Human colour and light synthesis. Towards a coherent field of knowledge was carried out during 2010-11. Colour and light experts from Nordic universities and companies investigated different aspects of the spatial interaction between colour and light and its importance for human beings. This paper deals with the general learnings from the process. Specific results are presented in other papers at this conference.
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| 9. |
- Arjomandi Rad, Mohammad, 1987, et al.
(författare)
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Image regression-based digital qualification for simulation-driven design processes, case study on curtain airbag
- 2023
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Ingår i: Journal of engineering design (Print). - : Taylor & Francis. - 0954-4828 .- 1466-1837. ; 34:1, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Today digital qualification tools are part of many design processes that make them dependent on long and expensive simulations, leading to limited ability in exploring design alternatives. Conventional surrogate modelling techniques depend on the parametric models and come short in addressing radical design changes. Existing data-driven models lack the ability in dealing with the geometrical complexities. Thus, to address the resulting long development lead time problem in the product development processes and to enable parameter-independent surrogate modelling, this paper proposes a method to use images as input for design evaluation. Using a case study on the curtain airbag design process, a database consisting of 60,000 configurations has been created and labelled using a method based on dynamic relaxation instead of finite element methods. The database is made available online for research benchmark purposes. A convolutional neural network with multiple layers is employed to map the input images to the simulation output. It was concluded that the showcased data-driven method could reduce digital testing and qualification time significantly and contribute to real-time analysis in product development. Designers can utilise images of geometrical information to build real-time prediction models with acceptable accuracy in the early conceptual phases for design space exploration purposes.
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| 10. |
- Axelson, Mattias, et al.
(författare)
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Collective action problems in public sector innovation: A business model perspective
- 2017
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Ingår i: Creativity and Innovation Management. - : Wiley. - 0963-1690 .- 1467-8691. ; 26:4, s. 370-378
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Tidskriftsartikel (refereegranskat)abstract
- We explore how the literature on business models can explain the outcomes of innovation attempts in the public sector. Our findings suggest that governments can access a well-developed knowledge domain for a public sector area but have a weak ability to propagate its value for society. Drawing on the business model literature concerning interdependence and distributed agency, we illustrate how a collective action problem related to innovation may arise in the public sector. We illustrate this new category of public innovation challenge with the (failed) case of the Swedish civil contingencies system and subsequently discuss a new line of inquiry for future research.
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